1. Field of the Invention
The present invention relates to a camera having a lens barrel in which a lens cover is automatically opened and closed in accordance with extension and collapse of the lens barrel.
2. Description of the Prior Art
Hitherto, there is known a camera in which an electric motor is driven so that when the camera is not used, an image taking lens is accommodated in a main frame of the camera, and when the camera is used, the image taking lens is extended from the main frame of the camera. Of such a type of camera, there is widely known a camera in which a lens cover is disposed in front of an image taking lens, and the lens cover is automatically opened and closed in accordance with a switching between accommodation and extension of the image taking lens. An example of such a camera is proposed in Japanese Patent Laid Open Gazette Hei. 7-49515.
According to a camera proposed in Japanese Patent Laid Open Gazette Hei. 7-49515, a lens cover is enabled by a spring force to be opened, and when an image taking lens is accommodated in the main frame of the camera, the lens cover is forcibly closed against the spring force. Generally, as compared with a term during which a camera is used, a term during which the camera is not used is overpoweringly longer. Consequently, in the camera proposed in Japanese Patent Laid Open Gazette Hei. 7-49515,a term during which the lens cover is closed against the spring is very long. For this reason, a load is applied for a long time to the spring enabling the lens cover. This raises sometimes a problem as to durability.
Further, according to a camera proposed in Japanese Patent Laid Open Gazette Hei. 7-49515, since a lens cover is enabled by a spring force to be opened, also in the event that an image taking lens is accommodated in the main frame of the camera and the lens cover is closed, a force to always open the lens cover is applied to the lens cover. Accordingly, for example, in an arrangement wherein a lens cover is divided into two pieces, in the event that components constituting a switching mechanism for the lens cover are wrong in production precision even a little bit, this causes a gap between joint surfaces of two pieces of the lens cover. Thus, there is such a defect that the gap may give the impression that it is uncomfortable in appearance. On the other hand, in order to avoid such a defect, it is considered that the production precision of components is improved, or alternatively the switching mechanism for the lens cover is provided with a mechanism for preventing an occurrence of the gap between two pieces of the lens cover. However, this involves a problem that the cost is increased.
It often happens that when the lens cover is closed, a user intends to forcibly open two pieces of the lens cover out of mere curiosity. As mentioned above, since the lens cover is enabled by a spring force to be opened, at the time when the lens cover is closed, a force against the enabling force of the spring is effected on the lens cover. Consequently, in the event that a user intends to forcibly open two pieces of the lens cover, there is the fear that the lens cover is destroyed. In order to avoid such a fear, there is a need to prepare additional components for buffering an external force applied to the lens cover. Also, this involves a problem that the cost is increased.
The camera proposed in Japanese Patent Laid Open Gazette Hei. 7-49515 incorporates thereinto a zoom lens having a two-stage lens barrel collapse structure. According to such a camera, in a lens barrel, there are provided a lens cover enabled by a spring force to be opened and a lens cover switching member for performing open and close of the lens cover. Further, according to such a camera, in a main frame of the camera, there is provided a lens cover switching affecting member which affects the lens cover switching member in such a manner that when the lens barrel is extended, the lens cover is opened, and when the lens barrel is collapsed, the lens cover is closed. In the state that the lens barrel is collapsed to be accommodated, the lens cover switching member and the lens cover switching affecting member are engaged with one another, so that the lens cover is closed against the spring. On the other hand, when the lens barrel is extended, an engagement of the lens cover switching member with the lens cover switching affecting member is removed, so that a force against the spring is released and the lens cover is opened.
Generally, a two-stage collapsible mount type of lens barrel is of a cylindrical structure in view of maintaining a precision and a high density structure. And on the other hand, a picture is of a rectangular configuration. If the camera proposed in Japanese Patent Laid Open Gazette Hei. 7-49515 is constructed under the conditions as mentioned above, there will occur restrictions in an arrangement position of the lens cover switching affecting member in the lens barrel, and in an arrangement position of the lens cover switching member. This brings about a problem that a camera is restricted in degree of freedom of design.